A magnetic recording medium used in a hard disk drive (HDD) is a recording medium for recording and reproducing information magnetically, and an improvement in its recording density is in progress. As a technique to improve the recording density of the magnetic recording medium, a patterned medium (bit patterned medium: BPM, for example) has been studied. The patterned medium is obtained by processing a continuous magnetic film to form a pattern (dot, for example). The patterned medium is being actively studied because it can reduce the thermal instability in a current magnetic recording medium made of a granular thin film.
A data area of the magnetic recording medium is usually divided into a plurality of zones in a radial direction for the purpose of efficient data handling. A marker is usually disposed at the boundary of these zones. By using a magnetic material as the marker, a signal from the marker is obtained when a magnetic head crosses the zones. This signal can be utilized as a trigger to know the change in the zones.
However, the information obtained from the marker when the magnetic head crosses the marker is not always sufficient.